Rain Events Research Articles

Reduction in the ratio of stemflow to rainfall during heavy rain in two Japanese cedar stands and the influence on rainfall partitioning

Stemflow (SF) and gross rainfall (GR) were measured in two Japanese cedar stands with stand densities (SDs) of 5700 trees/ha and 9700 trees/ha. SF water was collected from four trees in each stand, and SF was derived by dividing the volume by the canopy area of the trees. In previous studies the highest SD for SF measurements in Japanese cedar and cypress was 2500 trees/ha with SF/GR of 23.3%. In this study SF/GR in the 5700-trees/ha and the 9700-trees/ha stands were 34.0% and 53.3%, respectively. Literature data together with the results of this study showed linear relationship between SF/GR and SD. In both cedar stands SF increased linearly with increasing GR on a rain event basis, however, a bending point in linearity that is defined as a threshold appeared for GR > 100 mm in the 9700-trees/ha stand, over which the slopes of the regression line became gentler. The 10-minute analyses also revealed the threshold and gentler slope of the regression line during intense rainfall. The threshold values were not constant but ranged from 4 to 8 mm/10 min. One of the causes of the threshold is splash droplets generated by raindrops hitting canopy and trunks, and another is SF water that breaks away from branches and stems. Both of them become throughfall (TF) and reduce rainwater allocated to SF during intense rainfall. The past measurements on TF and canopy interception (CI) conducted at the same site as this study showed the threshold, over which CI/GR increased. The existence of the threshold in CI/GR means some rainwater that was not allocated to SF but became TF evaporated as splashes before reaching the forest floor. Reduction in SF/GR influences rainfall partitioning in the stands.

Insights on seasonal solifluction processes in warm permafrost Arctic landscape using a dense monitoring approach across adjacent hillslopes

Solifluction processes in the Arctic are highly complex, introducing uncertainties in estimating current and future soil carbon storage and fluxes, and assessment of hillslope and infrastructure stability. This study aims to enhance our understanding of triggers and drivers of soil movement of permafrost-affected hillslopes in the Arctic. To achieve this, we established an extensive soil deformation and temperature sensor network, covering 48 locations across multiple hillslopes within a 1 km2 watershed on the Seward Peninsula, AK. We report depth-resolved measurements down to 1.8 m depth for May to September 2022, a period conducive to soil movement due to deepening thaw layers and frequent rain events. Over this period, surface movements of up to 334 mm were recorded. In general, these movements occur close to the thawing front, and are initiated as thawing reaches depths of 0.4–0.75 m. The largest movements were observed at the top of the south-east facing slope, where soil temperatures are cold (mean annual soil temperatures averaging −1.13 °C) and slopes are steeper than 15°. Our analysis highlights three primary factors influencing movements: slope angle, soil thermal conditions, and thaw depth. The latter two significantly impact the generation of pore water pressures at the thaw–freeze interface. Specifically, soil thermal conditions govern the liquid water content, while thaw depth influences both the height of the water column and, consequently, the pressure at the thawing front. These factors affect soil properties, such as cohesion and internal friction angle, which are crucial determinants of slope stability. This underscores the significance of a precise understanding of subsurface thermal conditions, including spatial and temporal variability in soil temperature and thaw depth, when assessing and predicting slope instabilities. Based on our observations, we developed a factor of safety proxy that consistently falls below the triggering threshold for all probes exhibiting displacements exceeding 50 mm. This study offers novel insights into patterns and triggers of hillslope movements in the Arctic and provides a venue to evaluate their impact on soil redistribution.

Hazard Analysis and Vulnerability Assessment of Cultural Landscapes Exposed to Climate Change-Related Extreme Events: A Case Study of Wachau (Austria)

The present paper aims to study the Wachau Valley in Austria as a representative Cultural Landscape under threat from extreme hydrometeorological hazards linked to climate change. The primary objective is to investigate the impacts and assess the vulnerability associated with the events of heavy rain and flooding. The methodology employed consists of an investigation of recorded past events impacting the Wachau; a vulnerability ranking system; a climate time series analysis based on earth observation products; and future hazard maps at territorial level, developed with outputs from regional and global climate models. The investigation we carried out provides a vulnerability assessment of two terraced areas with a surface of about 10,000 m2 in total, characterized by the presence of dry stone walls, with different state of conservation in the Municipality of Krems (Wachau). In addition, climate projections at territorial level for the extreme climate indices R20mm, R95pTOT, and R×5day—selected for investigating the likelihood of increases/decreases in events of heavy rain and large basin flooding—are provided, with a spatial resolution of ~12 km for the near and far future (2021–2050; 2071–2100) under stabilizing (RCP 4.5) and pessimistic (RCP 8.5) scenarios. The results indicate a general increase for the three indices in the studied areas during the far future under the pessimistic scenario, suggesting a heightened risk of heavy rain and flooding. These findings aim to inform policymakers and decision-makers in their development of strategies for safeguarding cultural heritage. Furthermore, they serve to assist local stakeholders in enhancing their understanding of prioritizing interventions related to preparedness, emergency response, and recovery.

Microphysical Parameterization Scheme with Satellite Data Verification and Observation Data for Analysis of Heavy Rain in Yogyakarta City

The numerical weather prediction model Weather Research and Forecasting - Advanced Research WRF (WRF-ARW) was used to simulate the atmospheric conditions during heavy rainfall in the Yogyakarta area on February 3, 2022. Several parameterization schemes were compared with observational data to obtain the best choice of microphysical parameterization scheme in describing the atmospheric conditions at the time of the event. The microphysical parameterization schemes used are: Kessler, Purdue Lin, and WRF Single-Moment. Class (WSM3). The verification results show that the Kessler microphysical parameterization scheme has the best performance in representing heavy rain events with a fairly high low cloud fraction data accuracy value ranging from 0.3 - 0.4 and the highest rainfall modeling value is 8.3 mm. It can be concluded that the Kessler scheme is sufficient to model the occurrence of heavy rain in the city of Yogyakarta.

Meteorological Characteristics of a Continuous Ice-Covered Event on Ultra-High Voltage Transmission Lines in Yunnan Region in 2021

Yunnan plays a pivotal role in transmitting electricity from west to east within China’s Southern Power Grid. During 7–13 January 2021, a large-scale continuous ice-covering event of ultra-high voltage (UHV) transmission lines occurred in the Qujing area of eastern Yunnan Province. Based on ERA5 reanalysis data and meteorological observation data of UHV transmission line icing in China’s Southern Power Grid, the synoptic causes of the icing are comprehensively analyzed from various perspectives, including weather situations, vertical stratification of temperature and humidity, local meteorological elements, and atmospheric circulation indices. The results indicate a strong East Asian trough and a blocking high directing northern airflow southward ahead of the ridge. Cold air enters the Qujing area and combines with warm and moist air from the subtropical high pressure of 50–110° E. As warm and cold air masses form a quasi-stationary front over the northern mountainous area of Qujing due to topographic uplift, the mechanism of “supercooling and warm rain” caused by the “warm–cold” temperature profile structure leads to freezing rain events. Large-scale circulation indices in the Siberian High, East Asian Trough, and 50–110° E Subtropical High regions provided clear precursor signals within 0–2 days before the icing events.

The potential of soil microbial communities to transform deoxynivalenol in agricultural soils-a soil microcosm study.

Infestation of cereal fields with toxigenic Fusarium species is identified as an environmental source for the mycotoxin deoxynivalenol (DON). During rain events, DON may be washed off from infested plants and enter the soil, where microbial transformation may occur. Although some studies showed DON transformation potential of soil microbial communities in liquid soil extracts, these findings can not be transferred to environmental conditions. Accordingly, microbial transformation of DON in soil has to be investigated under realistic conditions, e.g., microcosms mimicking field situations. In this study, we investigated the potential of soil microbial communities to transform DON in six different agricultural soils at two levels (0.5 and 5 µg g-1). The dissipation and the formation of transformation products were investigated in a period of 35 days and compared to a sterilized control. In addition, we measured soil respiration and applied the phospholipid-derived fatty acid (PLFA) analysis to assess whether soil microbial community characteristics are related to the microbial transformation potential. Dissipation of DON in non-sterilized soils was fast (50% dissipation within 0.6-3.7 days) compared to the sterile control where almost no dissipation was observed. Thus, dissipation was mainly attributed to microbial transformation. We verified that small amounts of DON are transformed to 3-keto-deoxynivalenol (3-keto-DON) and 3-epi-deoxynivalenol (3-epi-DON), which were not detectable after 16-day incubation, indicating further transformation processes. There was a trend towards faster transformation in soils with active and large microbial communities and low fungi-to-bacteria ratio.

Rain splash-mediated dispersal of Escherichia coli from fecal deposits to field-grown lettuce in the mid- and south Atlantic U.S. regions is affected by mulch type.

Wildlife feces can contaminate vegetables when enteric bacteria are released by rain and splashed onto crops. Regulations require growers to identify and not harvest produce that is likely contaminated, but U.S. federal standards do not define dimensions for no-harvest zones. Moreover, mulching, used to retain soil moisture and maximize crop yield may impact rain-mediated bacterial dispersal from feces. To assess Escherichia coli dissemination from a fecal point source to lettuce grown on various mulches, lettuce cv. 'Magenta' was transplanted into raised beds with plastic, biodegradable plastic, straw, or left uncovered at field sites in Maryland and Georgia. Eleven days post-transplant, 10g of rabbit manure spiked with ~8 log CFU g-1 E. coli were deposited in each bed. One day following natural or simulated rain events, lettuce was sampled along 1.5m transects on either side of fecal deposits. Lettuce-associated E. coli was semi-quantified with an MPN assay and dependence on fecal age (stale or fresh), lettuce age (baby leaf or mature head), distance from point source, mulch and post-rain days were statistically evaluated. Distance (p<0.001), fecal age (p<0.001) and mulch (p<0.01) were factors for E. coli transfer from point source to lettuce. The highest and lowest E. coli estimates were measured from lettuce grown on biodegradable plastic and straw, respectively, with a 2-log MPN difference (p<0.001). Mulch and distance were also significant factors in E. coli recovery 3 days post-rain (both p<0.001), where plastic mulches differed from bare ground and straw (p<0.01). For all treatments, fewer E. coli were retrieved from lettuce at 0.3m, 3 days post-rain compared to 1 day (p<0.001). Fitting the data to a Weibull Model predicated that a 7-log reduction in E. coli from fecal levels would be achieved at 1.2-1.4m from the point source on plastic mulches, 0.75m on bare soil (p<0.05) and 0.43m on straw (p<0.01). Straw and bare ground limited rain-mediated E. coli dispersal from feces to lettuce compared to plastic mulches. Fecal age was negatively associated with E. coli dispersal. These findings can inform harvesting recommendations for measures related to animal intrusion in vegetable production areas.

Rainfall as a driver for near-surface turbulence and air-water gas exchange in freshwater aquatic systems.

Gas fluxes from aquatic ecosystems are a significant component of the carbon cycle. Gas exchange across the air-water interface is regulated by near-surface turbulence and can be controlled by different atmospheric forcing conditions, with wind speed and surface buoyancy flux being the most recognized drivers in empirical studies and modeling approaches. The effect of rainfall on near-surface turbulence has rarely been studied and a consistent relationship between rain rate and near-surface turbulence has not yet been established. In this study, we addressed some limitations still present in the quantitative understanding of the effect of rain rate on near-surface turbulence and on the resulting gas transfer velocity in freshwater. We performed controlled laboratory experiments over a wide range of rain rates (7 to 90 mm h-1) and estimated gas transfer velocities from high-resolution measurements of O2 concentration, while rain-induced turbulence was characterized based on particle image velocimetry. We found that the rain-induced dissipation rates of turbulent kinetic energy declined with depth following a consistent power-law relationship. Both energy dissipation rates and gas transfer velocity increased systematically with the rain rate. The results confirm a causal relationship between rainfall, turbulence, and gas exchange. We propose a power-law relationship between near-surface turbulent dissipation rates and rain rate. In combination with surface renewal theory, we derived a direct relationship between gas transfer velocity and rain rate, which can be used to assess the importance of short-term drivers, such as rain events, on gas dynamics and biogeochemical cycling in aquatic ecosystems.

Validating IMERG data for diurnal rainfall analysis across the Indonesian maritime continent using gauge observations

The availability of surface rainfall data with high spatial-temporal resolution is needed to understand the diurnal rainfall characteristics in the Indonesian Maritime Continent (IMC) to improve the accuracy of weather and climate models in this region. This study validates the accuracy of the Final Run product of IMERG data version 06B (V06B) and version 07A (V07A), which have a resolution of 0.1°–30 min for diurnal rainfall analysis over IMC. Validation was conducted for precipitation amount (PA), precipitation frequency (PF), and precipitation intensity (PI), by recording 302 automatic rain gauges (RG) every 10 min from January 2014 to September 2021. IMERG V06B and V07A perform well in observing diurnal PA and PF but struggle in observing diurnal PI compared to RG observations. This has been determined by the correlation coefficient (CC) values of IMERG V06B (V07) data, which are 0.76 (0.72) for PA, 0.77 (0.76) for PF, and 0.21 (0.13) for PI. The IMERG data align to an extent with RG observations for the PA value, having a small relative bias (RB). The results also display a systematic PF and PI values error. The high false alarm ratio (FAR) of IMERG data suggests rain detection errors, leading to overestimated PF values. Additionally, the underestimation of PI values is due to the limitation of IMERG data in observing extreme and small-scale rain events. About 86.10% (78.14%) and 81.45% (81.78) of IMERG V06B (IMERG V07A) data show a peak time difference of <3h for PA and PF when compared with RG observations. Overall, IMERG V06B performs better than V07, possibly due to inaccurate orbits of GPROF data, removal of SAPHIR satellite observations, and inter-calibration issues with CORRA and GPCP data. Continuous monitoring and data improvements are necessary to improve the accuracy and reliability of IMERG data in detecting diurnal rainfall patterns in the IMC region.

A class of photosensitizer highly effective to control bacterial infection in plants even on rainy days with dim light

Bacterial infections of plants are widespread and highly virulent, causing serious economic losses in agricultural production worldwide. These infections become particularly prevalent during rainy weather, characterized by high humidity and low light intensity (about 2–10% of a sunny day). Here we identified a class of photosensitizers that were effective in inhibiting plant bacterial infections under rainy weather with dim light. One of these compounds, compound 1, demonstrated exceptional efficacy by eliminating more than 4 logs (99.99%) of either Xanthomonas perforans or Xanthomonas citri subsp. citri (Xcc) strain at a concentration of 6.25 μM under rainy weather conditions with a light exposure of 28.51 J/cm2. For Clavibacter michiganensis (Cm), compound 1 demonstrated a comparable bactericidal effect at a lower concentration of 3.13 μM. Furthermore, compound 1 was effective in controlling plant leaf infections during rainy weather. Moreover, compound 1 exhibited a potent inhibitory effect on the biofilms pertinent to tomato spot disease and citrus canker under natural illumination on rainy days. Additionally, compound 1 displayed remarkable resilience to rain-wash on plant leaves, retaining 41.20% of its initial concentration following exposure to three simulated rain events. These findings provide a new strategy for plant pathogen disease management highlight its feasibility even during rainy weather.

Validation of WRF Rainfall Model during the November 4th, 2021 Flash Flood Event in Batu City – Indonesia

Flash floods in Batu City, Indonesia on November 4th, 2021, caused damage to property, agricultural land, settlements, death of livestock, and loss of human life. One of the important factors triggering this flash flood is heavy rainfall. This study aims to analyse the spatial and temporal dynamics of rainfall as a trigger for the event. Rainfall modelling was conducted using the WRF model with 2 microphysical schemes and 3 cumulus schemes. The data used is GFS data on October 30th, 2021, with a resolution of 0.25 x0.25 degrees which is used to predict rain events until November 4, 2021. Contingency table verification, RMSE value verification, and verification using tolerance limits are used to verify the results of modelling data based on BMKG observation data. The results of this study show that this model can predict rain and non-rain events very well. However, this model is not good enough to predict the thickness of rain until November 4, 2021. The best scheme in modelling rainfall is scheme 5 (Lin and Betts Miller Janjic). Scheme 5 has the smallest RMSE value of 77, the data fit is appropriate and the medium error rate in scheme 5 is 84%. Scheme 5 with GFS data input started from 02 November 2021 can record rain events on 04 November 2021 with extreme rain categories. This extreme rain is influenced by convective clouds. The temperature of the cloud tops changes significantly from 13.00 WIB to 14.00 local time, namely from −4 degrees, and decreases to −76 degrees Celsius.

Experimental effect of wind and heavy rain on increased splash erosion using rainfall simulator

To investigate the erosion process that occurs, rainfall simulation is used with a model scale for natural rain events in laboratory conditions. The calculation of erosion and any soil erosion with a slope setting of 5% was carried out experimentally on a laboratory scale using a rain simulator and adding wind using a 2-inch snail blower. Experiments carried out in the laboratory included erosion tests driven by rain and erosion tests by rain, which were given additional wind variables. Rain intensity used for testing is using discharge 1 litre/minute,1.5 litre/minute, and 2 litre/minute as a representative variation of rainfall. The occurrence of rain and wind simultaneously within a certain period will cause greater loss of soil. Although many studies have been conducted on the effects of rain and the combined effects of wind on soil erosion, only a limited number of studies have focused on the combination of the two variables that occur together. The results showed that in the applied rain intensity and wind factor, the collision of the kinetic energy of the rain driven by the wind resulted in higher erosion when compared to that without the influence of the wind.

Cross-Correlation among Seismic Events, Rainfalls, and Carbon Dioxide Anomalies in Spring Water: Insights from Geochemical Monitoring in Northern Tuscany, Italy

Variations in the CO2 dissolved in water springs have long been observed near the epicenters of moderate and strong earthquakes. In a recent work focused on data collected during the 2017–2021 period from a monitoring site in the Northern Apennines, Italy, we noticed a significant correlation between CO2 anomalies and moderate-to-weak seismic activity. Here, we extended this analysis by focusing on data collected from the same site during a different period (2010–2013) and by integrating the CENSUS method with an artificial neural network (ANN) in the already-tested protocol. As in our previous work, a fit of the computed residual CO2 distributions allowed us to evidence statistically relevant CO2 anomalies. Thus, we extended a test of the linear dependence of these anomalies to seismic events over a longer period by means of binary correlations. This new analysis also included strong seismic events. Depending on the method applied, we observed different time lags. Specifically, using the CENSUS methodology, we detected a CO2 anomaly one day ahead of the earthquake and another anomaly eleven days ahead. However, no anomaly was observed with the ANN methodology. We also investigated possible correlations between CO2 concentrations and rain events and between rain events and earthquakes, highlighting the occurrence of a CO2 anomaly one day after a rain event of at least 10 mm and no linear dependence of seismic and rain events. Similar to our previous work, we achieved a probability gain of around 4, which is the probably of earthquake increases after CO2 anomaly observations.

Performance of the Thies Clima 3D Stereo Disdrometer: Evaluation during Rain and Snow Events.

Imaging disdrometers are widely used in field campaigns to provide information on the shape of hydrometeors, together with the diameter and the fall velocity, which can be used to derive information on the shape-size relations of hydrometeors. However, due to their higher price compared to laser disdrometers, their use is limited to scientific research purposes. The 3D stereo (3DS) is a commercial imaging disdrometer recently made available by Thies Clima and on which there are currently no scientific studies in the literature. The most innovative feature of the 3DS is its ability in capturing images of the particles passing through the measurement volume, crucial to provide an accurate classification of hydrometeors based on information about their shape, especially in the case of solid precipitation. In this paper. the performance of the new device is analyzed by comparing 3DS with the Laser Precipitation Monitor (LPM) from the same manufacturer, which is a known laser disdrometer used in many research works. The data used in this paper were obtained from measurements of the two instruments carried out at the Casale Calore site in L'Aquila during the CORE-LAQ (Combined Observations of Radar Experiments in L'Aquila) campaign. The objective of the comparison analysis is to analyze the differences between the two disdrometers in terms of hydrometeor classification, number and falling speed of particles, precipitation intensity, and total cumulative precipitation on an event basis. As regards the classification of precipitation, the two instruments are in excellent agreement in identifying rain and snow; greater differences are observed in the case of particles in mixed phase (rain and snow) or frozen phase (hail). Due to the different measurement area of the two disdrometers, the 3DS generally detects more particles than the LPM. The performance differences also depend on the size of the hydrometeors and are more significant in the case of small particles, i.e., D < 1 mm. In the case of rain events, the two instruments are in agreement with respect to the terminal velocity in still air predicted by the Gunn and Kinzer model for drops with a diameter of less than 3 mm, while, for larger particles, terminal velocity is underestimated by both the disdrometers. The agreement between the two instruments in terms of total cumulative precipitation per event is very good. Regarding the 3DS ability to capture images of hydrometeors, the raw data provide, each minute, from one to four images of single particles and information on their size and type. Their number and coarse resolution make them suitable to support only qualitative analysis of the shape of precipitating particles.

Desiccation of undamaged grasses in the topsoil causes Namibia’s fairy circles – Response to Jürgens & Gröngröft (2023)

In a novel study, Getzin et al. (2022) have excavated 500 grasses at four regions of the Namib to systematically investigate the temporal process of how the young grasses die in fairy circles. Based on measurements of the root lengths, statistical testing, and comparative photo documentations the authors showed that sand termite herbivory did not cause the death of the freshly germinated grasses within fairy circles (FCs). Roots of those dead grasses were initially undamaged and even longer than those of the living grasses outside in the vegetation matrix, which is contrary to termite herbivory. The dying annual grasses within FCs had significantly higher root-to-shoot ratios than the vital grasses in the matrix, both of which can be attributed to the same grass-triggering rain event. This indicates that they died from water stress because the desiccating grasses invested biomass resources into roots, trying to reach the deeper soil layers with more moisture, but they failed.Jürgens and Gröngröft (2023) commented on our research findings. Here, we shed light on their statements by investigating the existing data evidence on the Namib fairy circles, which includes a thorough literature review about the proposed termite-feeding mechanism, as well as describing the properties of soil water within and around the FCs. Our review shows that there is no single study to date that has demonstrated with systematic field evidence in the form of root measurements and data from several regions of the Namib that the green germinating grasses within the FCs would be killed by root herbivory of sand termites.We emphasize that the top 10 cm of soil in the FCs is very susceptible to drying out. In this topsoil layer, the freshly germinated grasses with their 10 cm long roots die quickly after rainfall due to lack of water, because these small plants cannot reach and utilize the higher soil moisture content, which is only found in deeper soil layers below the dry topsoil. Based on 400 measurements of soil moisture during the rainy season 2024, we show that the topsoil in the FCs is significantly drier than in the matrix outside. Finally, we show that the soil physical conditions allow a very high hydraulic conductivity that supports the “uptake-diffusion feedback” during the first weeks after grass-triggering rainfall. During the first two weeks, the soil moisture at 20 cm depth ranged for several rainfall events between 9% and 18% within the FCs, hence way above the 6–8% threshold below which the hydraulic conductivity strongly declines. Even 20 days after rainfall, soil moisture was still above 8%. During this biologically active period, new grasses germinate after about five days, the large perennial grasses along the FC edge resprout and strongly draw water with their established root system at 20–30 cm depth, and the freshly germinated grasses in the FCs desiccate and die within 10–20 days. With our continuous soil moisture measurements, we argue that the quickly greening and competitively superior grasses on the FC edge, as well as the vital matrix grasses, draw soil water from the FCs. This rapid depletion of soil water and drying out of the topsoil leads to the death of the new grasses in the fairy circles.

β-D-glucuronidase activity triggered monitoring of fecal contamination using microbial and chemical source tracking markers at drinking water intakes

Intense rainfall and snowmelt events may affect the safety of drinking water, as large quantities of fecal material can be discharged from storm or sewage overflows or washed from the catchment into drinking water sources. This study used β-d-glucuronidase activity (GLUC) with microbial source tracking (MST) markers: human, bovine, porcine mitochondrial DNA markers (mtDNA) and human-associated Bacteroidales HF183 and chemical source tracking (CST) markers including caffeine, carbamazepine, theophylline and acetaminophen, pathogens (Giardia, Cryptosporidium, adenovirus, rotavirus and enterovirus), water quality indicators (Escherichia coli, turbidity) and hydrometeorological data (flowrate, precipitation) to assess the vulnerability of 3 drinking water intakes (DWIs) and identify sources of fecal contamination. Water samples were collected under baseline, snow and rain events conditions in urban and agricultural catchments (Québec, Canada). Dynamics of E. coli, HF183 and WWMPs were similar during contamination events, and concentrations generally varied over 1 order of magnitude during each event. Elevated human-associated marker levels during events demonstrated that urban DWIs were impacted by recent contamination from an upstream municipal water resource recovery facility (WRRF). In the agricultural catchment, mixed fecal pollution was observed with the occurrences and increases of enteric viruses, human bovine and porcine mtDNA during peak contaminating events. Bovine mtDNA qPCR concentrations were indicative of runoff of cattle-derived fecal pollutants to the DWI from diffuse sources following rain events. This study demonstrated that the suitability of a given MST or CST indicator depend on river and catchment characteristics. The sampling strategy using continuous online GLUC activity coupled with MST and CST markers analysis was a more reliable source indicator than turbidity to identify peak events at drinking water intakes.

Prehispanic Arid Zone Farming: Hybrid Flood and Irrigation Systems along the North Coast of Peru

As arid lands expand across the globe, scholars increasingly turn to the archaeological record for examples of sustainable farming in extreme environments. The arid north coast of Peru was the setting of early and intensive irrigation-based farming; it is also periodically impacted by sudden, heavy rainfall related to the El Niño Southern Oscillation (ENSO) phenomenon. While the sociopolitical effects, technologies, and engineering expertise of these irrigation systems have been thoroughly examined and theorized, little is known about how farmers managed periods of water stress. The aim of this study is to test whether arid zone farming was supported by hybrid, intermittent flood and perennial water source systems in the prehispanic past. An arroyo in the Chicama Valley was selected for preliminary data collection, and these data are presented here: (1) drone photography of the arroyo capturing the aftermath of a recent (2023) rain event; and (2) potassium (K) soil test kit results from samples collected near suspected prehispanic check dam features in the same area. The paper combines these data with comparative examples from the literature to suggest that the prehispanic features functioned as water-harvesting infrastructure. The paper concludes that sustainable, arid zone farming can be supported by hybrid, intermittent flood and perennial water source systems.

Nature-Inspired Regenerative Fine-Dust-Catching Coatings to Improve Air Quality.

Increased particulate matter (PM) concentrations in our ambient air are the cause of various life-threatening diseases and consequently need to be reduced to nonhazardous levels. The natural PM removal capabilities of leaves inspired the development of a low-cost coating technology that exploits natural weather phenomena for its PM catching and removal processes. The herein presented coating is based on microparticle-filled silicone with optimized chemical and physical surface properties. Its surface roughness was tuned using differently sized spray-dried particles, and its surface contact angle was adjusted through silicone tensides, polar ether groups incorporated in the silicon backbone, and the used amount of spray-dried particles. In such a way, optimized silicone coatings showed in laboratory experiments improved catching abilities (>300% relative to glass surfaces), a full retention of adsorbed PM during wind events, and the formation of large PM aggregates. Upon (simulated) rain events, these coatings were regenerated, and the content of harmful PM of various sizes dispersed in water was reduced between ∼73 and 100%. Furthermore, an outdoor test over 100 days showed the functioning of the coating under real-world conditions. These regenerative coatings are readily applicable on diverse surfaces and do not require any further technical infrastructure. Thus, they present an extension of the toolbox for PM reduction technologies.

The Pulses of Soil CO2 Emission in Response to Rainfall Events in Central Siberia: Revisiting the Overall Frost-Free Season CO2 Flux

Boreal forests nowadays act as a sink for atmospheric carbon dioxide; however, their sequestration capacity is highly sensitive to weather conditions and, specifically to ongoing climate warming. Extreme weather events such as heavy rainfalls or, conversely, heat waves during the growing season might perturb the ecosystem carbon balance and convert them to an additional CO2 source. Thus, there is an urgent need to revise ecosystem carbon fluxes in vast Siberian taiga ecosystems as influenced by extreme weather events. In this study, we focused on the soil CO2 pulses appearing after the rainfall events and quantification of their input to the seasonal cumulative CO2 efflux in the boreal forests in Central Siberia. Seasonal measurements of soil CO2 fluxes (both soil respiration and net soil exchange) were conducted during three consecutive frost-free seasons using the dynamic chamber method. Seasonal dynamics of net soil exchange fluxes demonstrated positive values, reflecting that soil respiration rates exceeded CO2 uptake in the forest floor vegetation layer. Moreover, the heavy rains caused a rapid pulse of soil emissions and, as a consequence, the release of additional amounts of CO2 from the soil into the atmosphere. A single rain event may cause a 5–11-fold increase of the NSE flux compared to the pre-rainfall values. The input of CO2 pulses to the seasonal cumulative efflux varied from near zero to 39% depending on precipitation patterns of a particular season. These findings emphasize the critical need for more frequent measurements of soil CO2 fluxes throughout the growing season which capture the CO2 pulses induced by rain events. This approach has inevitable importance for the accurate assessment of seasonal CO2 soil emissions and adequate predictions of response of boreal pine forests to climatic changes.

The Reintroduction of Brown Trout (Salmo trutta fario) in the Upper Scheldt River Basin (Flanders, Belgium): Success or Failure?

In 2017, the reintroduction of juvenile brown trout in the southwestern part of Flanders (the Zwalm River basin) (Belgium) was initiated. Monitoring during the subsequent years indicated that the released juveniles survived and matured, indicating that sufficient food and good habitat conditions were available. Despite recent fulfilment of free fish migration within the Zwalm River basin and several spawning habitats being present, no natural reproduction of brown trout could be observed. To obtain more insight into the reproduction and maturing of brown trout eggs under natural conditions, an in situ experiment was conducted during 3 consecutive years at 10 different sites within the river basin. The results of our research indicated that egg survival was generally low (&lt;5%). The main causes are most likely a heavy sediment load hampering sufficient oxygen and clean water flow through the redds. In this basin, the sediment load originates mainly from agricultural fields during heavy rain events and consequential run-off. Creating grassy and/or woody buffer strips along watercourses, in combination with changes in agricultural practices, is needed to be able to build up a viable and self-sustaining population of brown trout and also, in a larger context, of other rheophilic fish species.